drivers/oprofile/oprofilefs.c

   1 /**
   2  * @file oprofilefs.c
   3  *
   4  * @remark Copyright 2002 OProfile authors
   5  * @remark Read the file COPYING
   6  *
   7  * @author John Levon
   8  *
   9  * A simple filesystem for configuration and
  10  * access of oprofile.
  11  */
  12
  13 #include <linux/init.h>
  14 #include <linux/module.h>
  15 #include <linux/oprofile.h>
  16 #include <linux/fs.h>
  17 #include <linux/pagemap.h>
  18 #include <asm/uaccess.h>
  19
  20 #include "oprof.h"
  21
  22 #define OPROFILEFS_MAGIC 0x6f70726f
  23
  24 DEFINE_SPINLOCK(oprofilefs_lock);
  25
  26 static struct inode *oprofilefs_get_inode(struct super_block *sb, int mode)
  27 {
  28         struct inode *inode = new_inode(sb);
  29
  30         if (inode) {
  31                 inode->i_ino = get_next_ino();
  32                 inode->i_mode = mode;
  33                 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
  34         }
  35         return inode;
  36 }
  37
  38
  39 static const struct super_operations s_ops = {
  40         .statfs         = simple_statfs,
  41         .drop_inode     = generic_delete_inode,
  42 };
  43
  44
  45 ssize_t oprofilefs_str_to_user(char const *str, char __user *buf, size_t count, loff_t *offset)
  46 {
  47         return simple_read_from_buffer(buf, count, offset, str, strlen(str));
  48 }
  49
  50
  51 #define TMPBUFSIZE 50
  52
  53 ssize_t oprofilefs_ulong_to_user(unsigned long val, char __user *buf, size_t count, loff_t *offset)
  54 {
  55         char tmpbuf[TMPBUFSIZE];
  56         size_t maxlen = snprintf(tmpbuf, TMPBUFSIZE, "%lu\n", val);
  57         if (maxlen > TMPBUFSIZE)
  58                 maxlen = TMPBUFSIZE;
  59         return simple_read_from_buffer(buf, count, offset, tmpbuf, maxlen);
  60 }
  61
  62
  63 /*
  64  * Note: If oprofilefs_ulong_from_user() returns 0, then *val remains
  65  * unchanged and might be uninitialized. This follows write syscall
  66  * implementation when count is zero: "If count is zero ... [and if]
  67  * no errors are detected, 0 will be returned without causing any
  68  * other effect." (man 2 write)
  69  */
  70 int oprofilefs_ulong_from_user(unsigned long *val, char const __user *buf, size_t count)
  71 {
  72         char tmpbuf[TMPBUFSIZE];
  73         unsigned long flags;
  74
  75         if (!count)
  76                 return 0;
  77
  78         if (count > TMPBUFSIZE - 1)
  79                 return -EINVAL;
  80
  81         memset(tmpbuf, 0x0, TMPBUFSIZE);
  82
  83         if (copy_from_user(tmpbuf, buf, count))
  84                 return -EFAULT;
  85
  86         spin_lock_irqsave(&oprofilefs_lock, flags);
  87         *val = simple_strtoul(tmpbuf, NULL, 0);
  88         spin_unlock_irqrestore(&oprofilefs_lock, flags);
  89         return count;
  90 }
  91
  92
  93 static ssize_t ulong_read_file(struct file *file, char __user *buf, size_t count, loff_t *offset)
  94 {
  95         unsigned long *val = file->private_data;
  96         return oprofilefs_ulong_to_user(*val, buf, count, offset);
  97 }
  98
  99
 100 static ssize_t ulong_write_file(struct file *file, char const __user *buf, size_t count, loff_t *offset)
 101 {
 102         unsigned long value;
 103         int retval;
 104
 105         if (*offset)
 106                 return -EINVAL;
 107
 108         retval = oprofilefs_ulong_from_user(&value, buf, count);
 109         if (retval <= 0)
 110                 return retval;
 111
 112         retval = oprofile_set_ulong(file->private_data, value);
 113         if (retval)
 114                 return retval;
 115
 116         return count;
 117 }
 118
 119
 120 static int default_open(struct inode *inode, struct file *filp)
 121 {
 122         if (inode->i_private)
 123                 filp->private_data = inode->i_private;
 124         return 0;
 125 }
 126
 127
 128 static const struct file_operations ulong_fops = {
 129         .read           = ulong_read_file,
 130         .write          = ulong_write_file,
 131         .open           = default_open,
 132         .llseek         = default_llseek,
 133 };
 134
 135
 136 static const struct file_operations ulong_ro_fops = {
 137         .read           = ulong_read_file,
 138         .open           = default_open,
 139         .llseek         = default_llseek,
 140 };
 141
 142
 143 static int __oprofilefs_create_file(struct super_block *sb,
 144         struct dentry *root, char const *name, const struct file_operations *fops,
 145         int perm, void *priv)
 146 {
 147         struct dentry *dentry;
 148         struct inode *inode;
 149
 150         dentry = d_alloc_name(root, name);
 151         if (!dentry)
 152                 return -ENOMEM;
 153         inode = oprofilefs_get_inode(sb, S_IFREG | perm);
 154         if (!inode) {
 155                 dput(dentry);
 156                 return -ENOMEM;
 157         }
 158         inode->i_fop = fops;
 159         d_add(dentry, inode);
 160         dentry->d_inode->i_private = priv;
 161         return 0;
 162 }
 163
 164
 165 int oprofilefs_create_ulong(struct super_block *sb, struct dentry *root,
 166         char const *name, unsigned long *val)
 167 {
 168         return __oprofilefs_create_file(sb, root, name,
 169                                         &ulong_fops, 0644, val);
 170 }
 171
 172
 173 int oprofilefs_create_ro_ulong(struct super_block *sb, struct dentry *root,
 174         char const *name, unsigned long *val)
 175 {
 176         return __oprofilefs_create_file(sb, root, name,
 177                                         &ulong_ro_fops, 0444, val);
 178 }
 179
 180
 181 static ssize_t atomic_read_file(struct file *file, char __user *buf, size_t count, loff_t *offset)
 182 {
 183         atomic_t *val = file->private_data;
 184         return oprofilefs_ulong_to_user(atomic_read(val), buf, count, offset);
 185 }
 186
 187
 188 static const struct file_operations atomic_ro_fops = {
 189         .read           = atomic_read_file,
 190         .open           = default_open,
 191         .llseek         = default_llseek,
 192 };
 193
 194
 195 int oprofilefs_create_ro_atomic(struct super_block *sb, struct dentry *root,
 196         char const *name, atomic_t *val)
 197 {
 198         return __oprofilefs_create_file(sb, root, name,
 199                                         &atomic_ro_fops, 0444, val);
 200 }
 201
 202
 203 int oprofilefs_create_file(struct super_block *sb, struct dentry *root,
 204         char const *name, const struct file_operations *fops)
 205 {
 206         return __oprofilefs_create_file(sb, root, name, fops, 0644, NULL);
 207 }
 208
 209
 210 int oprofilefs_create_file_perm(struct super_block *sb, struct dentry *root,
 211         char const *name, const struct file_operations *fops, int perm)
 212 {
 213         return __oprofilefs_create_file(sb, root, name, fops, perm, NULL);
 214 }
 215
 216
 217 struct dentry *oprofilefs_mkdir(struct super_block *sb,
 218         struct dentry *root, char const *name)
 219 {
 220         struct dentry *dentry;
 221         struct inode *inode;
 222
 223         dentry = d_alloc_name(root, name);
 224         if (!dentry)
 225                 return NULL;
 226         inode = oprofilefs_get_inode(sb, S_IFDIR | 0755);
 227         if (!inode) {
 228                 dput(dentry);
 229                 return NULL;
 230         }
 231         inode->i_op = &simple_dir_inode_operations;
 232         inode->i_fop = &simple_dir_operations;
 233         d_add(dentry, inode);
 234         return dentry;
 235 }
 236
 237
 238 static int oprofilefs_fill_super(struct super_block *sb, void *data, int silent)
 239 {
 240         struct inode *root_inode;
 241         struct dentry *root_dentry;
 242
 243         sb->s_blocksize = PAGE_CACHE_SIZE;
 244         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
 245         sb->s_magic = OPROFILEFS_MAGIC;
 246         sb->s_op = &s_ops;
 247         sb->s_time_gran = 1;
 248
 249         root_inode = oprofilefs_get_inode(sb, S_IFDIR | 0755);
 250         if (!root_inode)
 251                 return -ENOMEM;
 252         root_inode->i_op = &simple_dir_inode_operations;
 253         root_inode->i_fop = &simple_dir_operations;
 254         root_dentry = d_alloc_root(root_inode);
 255         if (!root_dentry) {
 256                 iput(root_inode);
 257                 return -ENOMEM;
 258         }
 259
 260         sb->s_root = root_dentry;
 261
 262         oprofile_create_files(sb, root_dentry);
 263
 264         // FIXME: verify kill_litter_super removes our dentries
 265         return 0;
 266 }
 267
 268
 269 static struct dentry *oprofilefs_mount(struct file_system_type *fs_type,
 270         int flags, const char *dev_name, void *data)
 271 {
 272         return mount_single(fs_type, flags, data, oprofilefs_fill_super);
 273 }
 274
 275
 276 static struct file_system_type oprofilefs_type = {
 277         .owner          = THIS_MODULE,
 278         .name           = "oprofilefs",
 279         .mount          = oprofilefs_mount,
 280         .kill_sb        = kill_litter_super,
 281 };
 282
 283
 284 int __init oprofilefs_register(void)
 285 {
 286         return register_filesystem(&oprofilefs_type);
 287 }
 288
 289
 290 void __exit oprofilefs_unregister(void)
 291 {
 292         unregister_filesystem(&oprofilefs_type);
 293 }